Dynamic JVM detection

[apjanke]

Right now, Octave on macOS is built against a specific version and update of the JVM.

See if we can get upstream to add in dynamic JVM detection, and pull that in as a patch.

References:

• http://lists.gnu.org/archive/html/octave-maintainers/2012-12/msg00093.html
• https://savannah.gnu.org/bugs/?40111

[apjanke]

I put together a patch to do this in upstream.

Upstream bug report: https://savannah.gnu.org/bugs/index.php?54219

[apjanke]

Moved the milestone for this to The Future. It requires upstream Octave changes, and these didn't make it in to Octave 4.4.0 or 4.4.1.

[apjanke]

Sigh. This is even more of an inconvenience than I thought: Oracle does not provide downloads for the older versions of JDK 8. They're up to JDK 8 u191 now, so the JDK 8 u181 installer is no longer available for download. But our Octave 4.4.0 release was built against JDK 8 u181. Which means that users who haven't happened to have previously installed JDK 8 u181 don't have a way of getting Java to work with our 4.4.0 distribution.

I think this applies to the Homebrew-supplied bottles for Octave, too.

I'll nudge upstream on this when I have some spare time.

[apjanke]

Upstream has added support for JAVA_HOME, so at least we could detect and set that in our launcher wrapper script: https://savannah.gnu.org/bugs/?40111. It'll be available in 5.0.

[apjanke]

Moving this to Low priority, since I haven't seen any users asking for better Java support.

[apjanke]

Upstream merged a patch to fix this; it'll come out in the next major Octave release. Closing as fixed.